Contacts between Nubians and Arabs long predated the coming of Islam, but the arabization of the Nile Valley was a gradual process that occurred over a period of nearly 1,000 years. Arab nomads continually wandered into the region in search of fresh pasturage, and Arab seafarers and merchants traded in Red Sea ports for spices and slaves. Intermarriage and assimilation also facilitated arabization. After the initial attempts at military conquest failed, the Arab commander in Egypt, Abd Allah ibn Saad, concluded the first in a series of regularly renewed treaties with the Nubians that, with only brief interruptions, governed relations between the two peoples for more than 600 years. So long as Arabs ruled Egypt, there was peace on the Nubian frontier however, when non-Arabs acquired control of the Nile Delta, tension arose in Upper Egypt.

The Arabs realized the commercial advantages of peaceful relations with Nubia and used the treaty to ensure that travel and trade proceeded unhindered across the frontier. The treaty also contained security arrangements whereby both parties agreed that neither would come to the defense of the other in the event of an attack by a third party. The treaty obliged both to exchange annual tribute as a goodwill symbol, the Nubians in slaves and the Arabs in grain. This formality was only a token of the trade that developed between the two, not only in these commodities but also in horses and manufactured goods brought to Nubia by the Arabs and in ivory, gold, gems, gum arabic, and cattle carried back by them to Egypt or shipped to Arabia.

Acceptance of the treaty did not indicate Nubian submission to the Arabs, but the treaty did impose conditions for Arab friendship that eventually permitted Arabs to achieve a privileged position in Nubia. For example, provisions of the treaty allowed Arabs to buy land from Nubians south of the frontier at Aswan. Arab merchants established markets in Nubian towns to facilitate the exchange of grain and slaves. Arab engineers supervised the operation of mines east of the Nile in which they used slave labor to extract gold and emeralds. Muslim pilgrims en route to Mecca traveled across the Red Sea on ferries from Aydhab and Sawakin, ports that also received cargoes bound from India to Egypt.

Traditional genealogies trace the ancestry of most of the Nile Valley's mixed population to Arab tribes that migrated into the region during this period. Even many non-Arabic-speaking groups claim descent from Arab forebears. The two most important Arabic-speaking groups to emerge in Nubia were the Jaali and the Juhayna (see Ethnic Groups , ch. 2). Both showed physical continuity with the indigenous pre-Islamic population. The former claimed descent from the Quraysh, the Prophet Muhammad's tribe. Historically, the Jaali have been sedentary farmers and herders or townspeople settled along the Nile and in Al Jazirah. The nomadic Juhayna comprised a family of tribes that included the Kababish, Baqqara, and Shukriya. They were descended from Arabs who migrated after the thi731 hirteenth century into an area that extended from the savanna and semidesert west of the Nile to the Abyssinian foothills east of the Blue Nile. Both groups formed a series of tribal shaykhdoms that succeeded the crumbling Christian Nubian kingdoms and that were in frequent conflict with one another and with neighboring non-Arabs. In some instances, as among the Beja, the indigenous people absorbed Arab migrants who settled among them. Beja ruling families later derived their legitimacy from their claims of Arab ancestry.

Although not all Muslims in the region were Arabic-speaking, acceptance of Islam facilitated the arabizing process. There was no policy of proselytism, however, and forced conversion was rare. Islam penetrated the area over a long period of time through intermarriage and contacts with Arab merchants and settlers. Exemption from taxation in regions under Muslim rule also proved a powerful incentive to conversion.

Data as of June 1991